Pickup-arm control in automatic record-playing devices



June 23, 1970 E,T, HUMBY 3,515,677

PICKUP-ARM CONTROL IN AUTOMATIC RECORD-PLAYING DEVICES Filed July 9, 1968 8 She e`tsSheet l June 23, 1970 E. T. HUMBY 3,516,677

PICKUP-ARM CONTROL IN AUTOMATIC RECORD-PLAYING DEVICES Filed July 9,1968 a sheets-smet n United States Patent O 3,516,677 PICKUP-ARM CONTROL IN AUTOMATIC RECORD-PLAYING DEVICES Edward Thomas Humby, Swindon, England, assignor to The Plessey Company Limited, Ilford, England, a British company Filed July 9, 1968, Ser. No. 743,518 Claims priority, application Great Britain, July 14, 1967, 32,574/ 67 Int. Cl. G11b 3/08 U.S. Cl.- 274-9 5 Claims ABSTRACT OF THE DISCLOSURE In a gramophone record changer drive for the movement of the pickup arm is transmitted to the arm from a drive plate which is actuated for one forward-and-return stroke for each record-changing cycle, by a coupling link, which is frictionally pivoted to the drive plate and has a shaped slot which embraces the coupling pin and has on each side a step for respective driving engagement with the pin during the forward and return stroke.

A fixed abutment stem and an edge-cam portion of the link co-operate to deect the link about its pivot to disengage the step of the first edge portion from the pin to stop the outward drive of the arm while permitting it to be moved further outwardly when the outwardly moving pickup arm reaches a predetermined position and to cause the step of the second edge portion to strike the pin and propel it, during the subsequent return stroke, in the direction producing inward movement of the arm, said lastmentioned step being so inclined to the direction of movement of the coupling pin as to be moved out of engagement with the pin by reaction forces when the pin is prevented from further movement in this direction, a further fixed abutment and a further edge-cam portion being provided for defiecting, at the end of the return stroke, the link to a position of readiness to re-engage the step of the first edge portion during the forward stroke of a subsequent record-changing cycle.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to automatic record-changer mechanisms of the kind in which a cam member, arranged to perform a single revolution for each record-changing operation, is employed to produce for each revolution of the cam mem'ber a single reciprocatory movement of a drive plate or equivalent member (hereinafter called drive plate), to which a member participating in the inward and outward movement of the pickup arm, hereinafter called the pickup plate, is arranged, after the termination of the playing of a record, to be coupled during movement of the drive plate in one direction-after the pickup has been lifted from the record, for example by the co-operation of a cam surface on the drive plate with an arm-lifting pin-until the arm has moved clear of the area of the largest record for which the player is intended, and also during a part of the subsequent opposite movement of the drive plate so that after a lapse of time in which a new record is arranged to be deposited on the turntable and in appropriate cases has effected the selection of a stylusdepositing position in accordance with the record diameter,

the still raised pickup arm is moved towards the centre of Y the record turntable until the stylus depositing position determined by the selection has been reached, whereafter the coupling means permit continuation of the movement of the drive-plate without further movement of the arm. By the time the pickup stylus has been actually deposited Mice on the record, it should .be free to follow the record groove with a minimum of resistance.

DESCRIPTION OF THE PRIOR ART In a known record-changer mechanism of the kind specified, the coupling of the drive plate to the pickup plate was effected by a slotted link which was pivotally attached at one end to the drive plate, while the slot was arranged to embrace a pin on the member movable with the arm, the end of the slot more remote from the first-mentioned pivot being made slightly narrower than the diameter of the pin of said member and this narrow portion was allowed to expand resiliently by longitudinally splitting the end of the link remote from the pivot attached to the drive plate. The length of the slot was so chosen that, when at the end of the outward movement of the arm, the member movable with the arm struck an abutment provided for the purpose, the pin was forced into the narrow portion of the slot and became frictionally clamped therein due to the above-mentioned resilience. During the subsequent movement of the drive plate in the opposite direction this friction was suicient to move the arm inwardly until its inward movement was terminated by a selector stop determining the selected stylus-depositing position, whereafter further movement of the drive plate in the last-mentioned direction moved the link relative to the coupling pin, causing the latter to leave the narrow portion of the slot and enter a wider portion, in which it was free to move without appreciable resistance.

SUMMARY OF THE INVENTION The present invention has for an object to provide an improved mechanism for coupling the pickup plate to the drive plate, which permits the frictional coupling causing outward movement of the pickup plate to be terminated and the frictional coupling causing inward movement of the pickup plate to be initiated without relying on a stop arresting the outward movement of the pickup arm. According to a broad aspect of the invention in an automatic record-changer mechanism of the kind specified a link for coupling the pickup plate to the drive plate is connected to the drive plate by a friction-loaded pivot connection and has a plurality of cam-edge portions facing opposite sides of its radial length including a first, and an oppositely facing second stop-like portion for respective co-operation with a pin or pins projecting from the pickup plate, the one portion during the first part of that stroke of the drive plate which serves to move the pickup arm clear of the turntable, and the other portion during the return stroke of the drive plate, a third steplike portion facing in the same direction as the first and arranged to co-operate with an abutment which is stationary, at least relative to a stationary plane perpendicular to the pivot axis of the link, to produce movement of the link about its frictional pivot connection to disengage said first step-like portion from its associated pin, and further cam-edge portions respectively co-operating with stationary abutments for guiding the first step into cooperation with its associated pin during the first-mentioned stroke of the drive plate, for guiding the second step into co-operation with its associated pin during the return stroke of the drive plate, and to move the link to a position allowing free movement of the pickup plate for moving the pickup to its innermost position on the turntable during the return stroke before completion of the deposition of the pickup on to the turntable for engagement of a record.

According to a somewhat more specific aspect the pickup plate is coupled to the drive plate by a flat link provided with a plurality of edge-cam surfaces and connected to the drive plate by a pivot subject to controlled friction,.one of said edge-cam surfaces forming a first step against which during the outward movement of the pickup arm a pin or like abutment, hereinafter called pin, of the pickup plate rests, and another edge-cam surface forming a second step which co-operates with an effectively stationary abutment member in such manner as to produce, at a predetermined point of the outward movement of the pickup plate, pivotal movement of the link member about its frictional pivot in such manner as to cause the said first step to clear the said pin so that further movement of the drive plate in the same direction will produce no further outward movement of the pickup arm, and a further edge-cam surface of said link forming a third step, this third step being so arranged, and the link itself being so guided by a further edge cam surface and also cooperating with a stationary abutment member, that during the return movement of the drive plate, after a predetermined angle of movement of the latter, the third step engages the same or another pin on the pickup plate to produce inward movement of the pickup arm, said third step being disposed at such an angle to the direction of movement of the link pivot relative to the last-mentioned pin as to allow when the inward movement of the pickup arm is terminated by a stop means in a selected position, the last-mentioned pin to ride over said third step, thereby moving the link pivotally relative to the drive plate, camming-action guide means being provided which after continued movement of the drive plate to a position causing the pickup stylus to be deposited on the record, provides clearance between said pin or pins and all edge portions of the link for free pickup-arm movement.

Preferably the rst and third step-cam surfaces are provided on opposite edges of an elongated opening in the link, and a single pin extending from the pickup plate is arranged to co-operate successively with the first and third step surfaces of the cam.

According to another preferred feature, the cam surfaces forming the second step, which produces disengagement of the first step from its associated pin, is arranged on the outer edge of the link at that side to which the rst step faces, and this second step preferably co-operates with an end portion of the arm-lifting pin. It will be appreciated that during the time of this co-operation the pickup arm is always lifted so that only a short end portion of the lifting pin is required to be clear for cooperation With said second step, while the remainder of the projecting length of the lifting pin may, for example, be encircled by a thrust spring ensuring contact of the end of the lifting pin with the lifting cam, which latter preferably forms part ofthe drive plate.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawing,

FIG. l illustrates one embodiment of the invention and is a somewhat diagrammatic underneath perspective view of the relevant parts of a record changer, in which the elements of the record changer mechanism not directly participating in the operation of the invention have been omitted in order to facilitate understanding of the invention, and

FIG. 2 is a plan view of a practical form of link plate.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, a turntable 2 is accommodated in a depression of a record-changer base plate 1 and is rotatable about its axis 2n. A so-called cycling cam 3 is arranged to perform a single revolution at the end of each playing cycle. A so-called drive plate 4 is pivoted to the base plate for movement about a pivot axis 5 and is actuated, to perform a reciprocation for each revolution of the cycling cam, by a roller 6 which is rotatable about a pin 7 on the drive plate, and which co-operates with a track 3a of the cam 3. A pickup arm 8 is movable jointly with a plate 10 which is arranged at the underside of the base plate and is hereinafter referred-to as pickup plate, about a pivot 9 in the base plate 1. A circumferential portion of the pickup plate is formed with a number of sawteeth or stop 11, and a selector stop 12 is arranged to be automatically set in such manner by each record as it moves to the turntable as to render one or another of the teeth 11 effective to terminate the inward movement of the pickup arm 8 during the arm-positioning movement, according to the diameter of the record. An arm-lifting pin 13 is slidably mounted in the base plate 1 at a short distance from the arm pivot axis 9, and the pickup plate 10 has an aperture 10a, through which the pin 13 passes to engage a face-cam portion 14 forming part of the drive plate 4 and having, in a known manner, a ramp 14a which, at the beginning of the stroke of the drive plate serving to move the pickup arm away from the turntable centre, causes the pin 13 and thus the arm 8 to be raised, while the remainder of the face-cam portion 14 is flat to maintain the arm in the raised position during both the outward and inward lateral swinging movements of the pickup arm, that is until the drive plate 4 during its return stroke approaches its illustrated position of rest, in which the pickup arm is free to follow the track of the record groove.

In order to produce requisite inward and outward movements of the pickup arm in accordance with the movement of the drive plate 4, the pickup plate 10 carries a coupling pin 15 which projects into a shaped elongated aperture or slot 17 of a at coupling link 18. This link, which is also shown in FIG. 2, is carried by the drive plate 4, to which it is connected by a friction -pivot 19, 19a. The edges of the slot 17, as well as the outer lateral edges of the link 18, are formed with cam portions for respective co-operation with the coupling pin 15, with the end portion of the arm-lifting pin 13, and with one or the other of two guide stems 20 and 21 in a manner which will now be described in more detail.

As already mentioned, the position of the parts as illustrated in FIG. l approximately corresponds to the rest position of the mechanism, that is to say to the position it assumes during the actual play of the record, when the cam 3, and accordingly also the drive plate 4, is stationary with the pin 13 allowed by the cam portion 14 to assume its lowermost position and with the cam-following roller 6 resting, under the action on the drive plate 4 of a spring 22, on the apex of the track in the cycling cam 3. When, at the end of the playing of a record, the pickup stylus reaches the running-out groove at the centre of the record, the cycling cam is, in a known manner, coupled to the turntable to perfrom one revolution. During the beginning of this revolution the roller 6 will move radially inwards towards the axis of the cam 3, causing the drive plate 4 to move pivotally in the direction of the arrow A, taking with it the link 18, due to the friction in the pivot 19, 19a until a portion 23 of the right-hand edge (as seen in the drawing) of the link 18 makes contact with the xed stem 20. During this movement the coupling pin 1S of the pickup plate 10 is clear of both edges of the slot 17, and during the corresponding part of the vmovement of the plate 4 the cam portion 14 will raise the pin 13, and With it the pickup arm, to clear the pickup stylus from the record grooves.

Once the edge portion 23 of the coupling link has made contact with the stem 20, further movement of the drive plate in the same direction will cause this edge portion 23 to slide along the stem 20, thereby producing gradual clockwise pivotal movement of the link in the friction pivot 19. The edge portion 23 and the opening 17 are so shaped and so arranged relative to each other that the resulting movement of the coupling link 18 will cause the pin 15 to strike a step-like surface portion 24 at the left-hand side of the slot 17, and the inclination of this portion to its direction of movement is so arranged that the surface portion 24 will act on the pin 15 to swing the pickup arm 8 outwardly away from the centre of the turntable. This outward movement of the arm will continue until, when the arm has reached a desired position clear of the largest records to be employed, a step portion 25 at the left-hand edge of the link 18 (as seen in FIG. 1) comes into engagement with the circumference of the lifting pin 13. Since this pin is only movable in an up and down direction, it acts on the step portion 25 as a fixed abutment and will, in sliding along the step portion 25, cause the link 18 to swing sharply in a clockwise direction about the friction pivot 19. As a result its step-like surface portion 24 will move out of engagement with the coupling pin 15 of the pickup plate and thus terminate the outward movement of the pickup arm. As the movement of the drive plate 4 and link 18 proceeds, the pin 15 will then enter a portion 26 of the slot 17 which is so shaped and arranged as to allow the movement of the drive plate 4 and link 18 to continue without affecting the arm position. When the innermost point of the cam track 3a is reached, the movement of the drive plate 4 is reversed, the plate now moving in the direction contrary to the arrow a, with the link 18 participating due to the friction in pivot 19, 19a, in its angular movement. As a result an edge portion 27 of the link 18, near the lower end of the left-hand side of the link as seen in FIG. 2, will shortly thereafter strike the second guide stem 21, which will force the link 18 to swing in an anti-clockwise direction relative to the drive plate 4 as first the edge portion 27 and then on adjoining concave edge portion 28 of the link 18 slides along the stem 21. As a result of this anti-clockwise movement of the coupling link 18, a step 29 on the left-hand side, as seen in FIG. l of the opening 17 will eventually strike the pin of the pickup-arm plate 10. The disposition of the step 29 is such relative to the direction in which the pin 15 can move about the pivot 9, that the step 29 will carry the pin with it and thus Imove the pickup arm plate 10, to which the pin 15 is fixed, in an anti-clockwise position to move the pickup arm 18 towards the centre of the turntable until the appropriate pickup put-down position, selected by the stop 12, is reached and the stop 12 prevents the pickup plate 10 from further pivotal movement. As a result, the pin 15 will then remain stationary, and the cam surface 29 will slide along the pin 15, moving the link 18 in an anti-clockwise direction about the pivot 19, 19a overcoming the friction of the latter, until the pin 15 reaches the inner end of the` step surface 29, where the shape of the opening 17 allows the link 18 to move into contact with the guide stem 21. Thereafter, during the final portion of this clockwise movement of the drive plate 4, the guide stem 21 co-operates with an edge portion 30 of the coupling link 18 to return the link 18 to its illustrated position, in which the pin 15 is clear by appreciable distances from both edges of the opening 17, before the ramp 14a on portion 14 of the drive plate 4 reaches the lifting pin 13 to allow the pickup stylus to be deposited in the record groove. It will be seen that when this takes place, there is no mechanical connection between the pickup plate 10 and the coupling link 18; during the actual play of the record the pickup arm is therefore completely free to follow the record groove with a minimum of resistance.

Various parts of the mechanism described may be modified in shape without departing from the scope of the invention as above outlined. Thus the surfaces which cooperate with the pickup arm plate may be arranged at the outer edges of the coupling link, the two outer edges being arranged to co-operate respectively with two separate coupling pins. In this case either different portions of the outer surfaces, or edge surfaces of an opening in the coupling link, may be employed to control the pivotal movement of the coupling link relative to the drive plate 4. In the latter arrangement a single guide stem may be used to perform the function of both stems 20 and 21.

What we claim is:

1. In an automatic record-changer mechanism having a mounting structure provided with means for supporting a turntable for rotation about a vertical turntable axis, a cycling wheel arranged to perform a single revolution for each record-changing cycle, a drive plate coupled to the cycling wheel to perform, during each revolution of the wheel, a single reciprocatory pivotal movement about a vertical axis, a pickup arm mounted for horizontal inward and outward movement towards and away from the turntable axis and for vertical raising and lowering movement, a pickup plate mounted to participate in the inward and outward horizontal movement of the pickup arm, and arm-raising and lowering means operative to raise the pickup arm during an initial portion of the forward stroke of the drive plate, then maintaining it raised during the remainder of the forward stroke and an adjoining initial part of the return stroke, and allowing it to descend and remain lowered during a nal part of the return stroke of the drive plate: the combination comprising coupling-pin means on the pick-up arm plate, a coupling link for co-operation with said coupling-pin means, a pivot connection between said link and the drive plate for frictional pivotal movement of the link about a pivot axis fixed relative to the drive plate, said link having a first edge portion and a second edge portion each extending mainly longitudinally of the link, said edge portions being so arranged on the link as to be respectively urged into co-operation with the coupling-pin means by the reaction friction of the said pivot connection during the forward and return stroke respectively of the drive plate, said pivot axis being so positioned on the drive plate as to move, during said strokes of the drive plate, in a directio nmainly longitudinal of the link, and said pivot axis being arranged on a radius of the pickup plate which extends transversely to said longitudinal direction of the link, said first edge portion having a projecting step facing the coupling-pin means during said forward stroke to move the pickup arm outwardly, and said second edge portion having a projecting step facing the pivot-pins means at such an angle during said return stroke, relative to the direction of movement of the pin, as to move the pickup plate for inward movement of the arm as far as the pickup plate is free to move, and to angularly displace the link about said pivot axis against the frictional resistance of said pivot connection to allow the step of said second edge portion to clear the coupling-pin means when the pickup plate is held against continuation of such movement, the mechanism further including abutment means, supported in the mounting structure against horizontal movement, and the link further having cam-edge portions so shaped and arranged as to co-operate with said abutment means to produce, during the forward stroke of the drive plate, movement of the link about said pivot axis to move said step of said first edge portion clear of the path of the coupling-pin means to terminate the transfer of outward movement to the pickup arm from the drive plate while permitting manual continuation of such outward movement of the pickup arm, and to move the step of said second edge portion into the path of the coupling pin means, andduring the return stroke of the drive plate to maintain, after the step of said second edge portion has disengaged the couplingpin means, the coupling-pin means clear of both said edge portions for unobstructed movement of the couplingpin means and pickup plate during the play of a record.

2. An automatic record changer as claimed in claim 1 wherein said first and second edge portions form the opposite sides of a slot in the coupling link, said coupling pin means extending through the said slot.

3. An automatic record changer as claimed in claim 2, wherein said cam edge portion and said further cam edge portion form part respectively of the outer sides of the coupling link.

4. An automatic record changer as claimed in claim 3, including a pickup-lifting pin guided in the mounting structure for up-and-down movement while being prevented from transverse movement, said pick-up-lifting pin being arranged to form abutment means for co-operation With References Cited Said rSt Cam-edge pOItOn. UNITED STATES PATENTS 5. An automatic record changer as claimed in claim 1,

wherein the coupling link is formed with a guideedge 3,243,188 3/1966 Caddy 274-10 th"t'l fh t d t th d' uS e H11 la Part 0 te Ouwar movemen of e rive 2,939,464 6/1960 Guest n 274-40 plate to keep said rst and second edge portions clear of the coupling pin means until said raising and lowering means have raised the arm from its playing position. HARRY N' HAROIAN Primary Examiner 

